Where will these PMG/Telecom Rotary Dial Phones work?

Anywhere in Australia on a standard telephone line. They may need an adaptor if you have RJ45 plugs (adaptors are here). They will not work on any digital line - e.g. digital PABX. They may or may not work as a VOIP phone on a router. The Router has to support decadic dialling at least, but this may not be enough.

All of the refurbished retro rotary dial phones and some (but not all) of the pushbutton phones dial Decadic, more info here.

They work fine on the same line as Broadband ADSL and ADSL 2+ (in fact they work better than modern phones) , infomation on ADSL and retro phones here